Endogenous Interaction Research Articles

Anti-Infective Peptides to Enhance the Host Innate Response: Design, Development and Delivery.

Inducible Nitric Oxide Synthase (iNOS or NOS2) produces Nitric Oxide (NO) and related reactive nitrogen species, which are critical effectors of the host innate response and play key roles in the intracellular killing of bacterial and parasitic pathogens. The SPRY domain- containing SOCS box proteins SPSB1 and SPSB2 are key physiological regulators of this important enzyme. Disrupting the endogenous SPSB-iNOS interaction should prolong the intracellular lifetime of iNOS and enhance the production of NO, and therefore be beneficial in treating chronic and persistent infections such as tuberculosis. By using structure-based design, potent peptide inhibitors of this interaction have been developed. Inhibitors of the SPSB-iNOS interaction have therapeutic potential as a novel class of anti-infective agents. Various strategies are being pursued to target these peptide inhibitors to macrophages and deliver them to the cytoplasm of these cells. It will then be possible to assess the efficacy of such inhibitors in boosting the capacity of macrophages to destroy infectious pathogens.

DISC1 and Its Protein Interactomes for Mental Function

SEE CORRESPONDING ARTICLE ON PAGE 305 Endogenous Cell Type–Specific Disrupted in Schizophrenia 1 Interactomes Reveal Protein Networks Associated With Neurodevelopmental DisordersBiological PsychiatryVol. 85Issue 4PreviewDisrupted in schizophrenia 1 (DISC1) has been implicated in a number of psychiatric diseases along with neurodevelopmental phenotypes such as the proliferation and differentiation of neural progenitor cells. While there has been significant effort directed toward understanding the function of DISC1 through the determination of its protein-protein interactions within an in vitro setting, endogenous interactions involving DISC1 within a cell type–specific setting relevant to neural development remain unclear. Full-Text PDF

Hedonic drinking engages a supraspinal inhibition of thermal nociception in adult rats.

The taste of sucrose is commonly used to provide pain relief in newborn humans and is innately analgesic to neonatal rodents. In adulthood, sucrose remains a strong motivator to feed, even in potentially hazardous circumstances (ie, threat of tissue damage). However, the neurobiological mechanisms of this endogenous reward-pain interaction are unclear. We have developed a simple model of sucrose drinking-induced analgesia in Sprague-Dawley rats (6-10 weeks old) and have undertaken a behavioral and pharmacological characterization using the Hargreaves' test of hind-paw thermal sensitivity. Our results reveal an acute, potent, and robust inhibitory effect of sucrose drinking on thermal nociceptive behaviour that unlike the phenomenon in neonates is independent of endogenous opioid signalling and does not seem to operate through classical descending inhibition of the spinal cord circuitry. Experience of sucrose drinking had a conditioning effect whereby the apparent expectancy of sucrose enabled water alone (in euvolemic animals) to elicit a short-lasting placebo-like analgesia. Sweet taste alone, however, was insufficient to elicit analgesia in adult rats intraorally perfused with sucrose. Instead, the sucrose analgesia phenomenon only appeared after conditioning by oral perfusion in chronically cannulated animals. This sucrose analgesia was completely prevented by systemic dosing of the endocannabinoid CB1 receptor antagonist rimonabant. These results indicate the presence of an endogenous supraspinal analgesic circuit that is recruited by the context of rewarding drinking and is dependent on endocannabinoid signalling. We propose that this hedonic sucrose-drinking model may be useful for further investigation of the supraspinal control of pain by appetite and reward.

Graphene Nanoflake Uptake Mediated by Scavenger Receptors.

The biological interactions of graphene have been extensively investigated over the last 10 years. However, very little is known about graphene interactions with the cell surface and how the graphene internalization process is driven and mediated by specific recognition sites at the interface with the cell. In this work, we propose a methodology to investigate direct molecular correlations between the biomolecular corona of graphene and specific cell receptors, showing that key protein recognition motifs, presented on the nanomaterial surface, can engage selectively with specific cell receptors. We consider the case of apolipoprotein A-I, found to be very abundant in the graphene protein corona, and observe that the uptake of graphene nanoflakes is somewhat increased in cells with greatly elevated expression of scavenger receptors B1, suggesting a possible mechanism of endogenous interaction. The uptake results, obtained by flow cytometry, have been confirmed using Raman microspectroscopic mapping, exploiting the strong Raman signature of graphene.

Proximity Ligation Assay (PLA) to Determine the Endosomal Localization of ESCRT Subunit in Virus-Infected Cells.

Proximity ligation assay (PLA) is a newly developed technique that outperforms the traditional immunoassays for visualizing the in situ endogenous protein-protein interactions and localizations and the activation of proteins in cell culture systems as well as in tissue sections. PLA, when combined with cellular marker staining, becomes a powerful approach to identify differential interaction of the proteins of endosomal sorting complex required for transport (ESCRT) at distinct stages of virus infection. In this chapter, we describe a PLA protocol to study the localization and interaction between the ESCRT protein TSG101 and endosomal markers in early stages of viral endocytosis in in vitro infected cells.

BRD4 interacts with PML/RARα in acute promyelocytic leukemia.

Bromodomain-containing 4 (BRD4) has been considered as an important requirement for disease maintenance and an attractive therapeutic target for cancer therapy. This protein can be targeted by JQ1, a selective small-molecule inhibitor. However, few studies have investigated whether BRD4 influenced acute promyelocytic leukemia (APL), and whether BRD4 had interaction with promyelocytic leukemia-retinoic acid receptor α (PML/RARα) fusion protein to some extent. Results from cell viability assay, cell cycle analysis, and Annexin-V/PI analysis indicated that JQ1 inhibited the growth of NB4 cells, an APL-derived cell line, and induced NB4 cell cycle arrest at G1 and apoptosis. Then, we used co-immunoprecipitation (co-IP) assay and immunoblot to demonstrate the endogenous interaction of BRD4 and PML/RARα in NB4 cells. Moreover, downregulation of PML/RARα at the mRNA and protein levels was observed upon JQ1 treatment. Furthermore, results from the RT-qPCR, ChIP-qPCR, and re-ChIP-qPCR assays showed that BRD4 and PML/RARα co-existed on the same regulatory regions of their target genes. Hence, we showed a new discovery of the interaction of BRD4 and PML/RARα, as well as the decline of PML/RARα expression, under JQ1 treatment.

A Study on Government Trust and Policy Plan for Real Estate Policy Change

본 연구에서는 우리나라 부동산 정책의 유형 및 특징, 변천사 등을 살펴보고, 역대정부의 부동산 정책이 주는 시사점을 제시하는 것이 연구의 목적이다. 기존의 정부신뢰에 관한 경험적 연구들은 대부분은 정권별 대통령과 정부정책에 대한 시민들의 평가에 대한 정치경제적 요인들을 비교분석하는 연구는 드물었다. 또한 많은 연구들은 변수 간에 서로 상호영향을 받는 내생성의 문제에 한정되어 있다. 하지만 본 연구의 연구결과 부동산 정책이 서민주거 안정이라는 측면과 더불어 국토 개발이나 건설투자 경기 활성화 등의 측면에 서도 중요한 정책이기 때문에 정부는 이러한 부동산 정책을 국정철학에 입각하여 명확한 장기비전과 원칙 하에 일관되게 추진되어야 한다는 정책방향이 설립되었다. 이를 위해 정책적 측면에서는 노후주택 관리, 적절한 임대주택 공급 등으로 가격과 거래, 공급에 급격한 변화가 발생하지 않도록 유도 및 대응 필요하다.The purpose of this study is to examine the types and characteristics of real estate policies in Korea and to show the implications of the real estate policy of the previous government. Empirical studies on existing government trust have rarely conducted comparative analysis of the political and economic factors of citizen s evaluation of presidential and governmental policies by regime. In addition, many studies are limited to the problem of endogenous interactions that are mutually influenced by variables. However, as a result of this study, the real estate policy is important in the aspect of stability of ordinary people s residence as well as in terms of development of land and revitalization of construction investment economy. Therefore, based on the philosophy of government, Policy direction was set up. In order to do this, it is necessary to induce and cope with the sudden change in price, transaction, and supply due to aged housing management and proper rental housing supply.

Assessing the green economy in China: An improved framework

Theses on China's low-carbon economy focus on the driving forces of carbon emissions, energy–carbon efficiency, and the carbon–economy nexus. Meanwhile, comprehensive frameworks that assess China's green economy and also analyze its driving forces are lacking. This paper constructs a green productivity index based on the Global Malmquist–Luenberger productivity index to evaluate the development of the low-carbon economy in China. A panel vector auto-regression model is adopted to further analyze the endogenous interactions and dynamic relationships among aspects of the green economy and its influencing factors. Empirical results show that China has seen a balanced development of green economic growth in 2000–2016, achieved in a series of clear stages. To maintain the sustainable growth of the low-carbon economy in the future, China must rely more on technological progress. This research also makes some important discoveries that have not been found in previous studies: the impact of China's industrial structure and energy consumption structure on the green economy are short term, having a duration of impact of approximately four years. Finally, we provide an assessment of provincial green economy development and describe the corresponding policy implications.

Loss of E-cadherin Enhances IGF1-IGF1R Pathway Activation and Sensitizes Breast Cancers to Anti-IGF1R/InsR Inhibitors.

Purpose: Insulin-like growth factor 1 (IGF1) signaling regulates breast cancer initiation and progression and associated cancer phenotypes. We previously identified E-cadherin (CDH1) as a repressor of IGF1 signaling and in this study examined how loss of E-cadherin affects IGF1R signaling and response to anti-IGF1R/insulin receptor (InsR) therapies in breast cancer.Experimental Design: Breast cancer cell lines were used to assess how altered E-cadherin levels regulate IGF1R signaling and response to two anti-IGF1R/InsR therapies. In situ proximity ligation assay (PLA) was used to define interaction between IGF1R and E-cadherin. TCGA RNA-seq and RPPA data were used to compare IGF1R/InsR activation in estrogen receptor-positive (ER+) invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC) tumors. ER+ ILC cell lines and xenograft tumor explant cultures were used to evaluate efficacy to IGF1R pathway inhibition in combination with endocrine therapy.Results: Diminished functional E-cadherin increased both activation of IGF1R signaling and efficacy to anti-IGF1R/InsR therapies. PLA demonstrated a direct endogenous interaction between IGF1R and E-cadherin at points of cell-cell contact. Increased expression of IGF1 ligand and levels of IGF1R/InsR phosphorylation were observed in E-cadherin-deficient ER+ ILC compared with IDC tumors. IGF1R pathway inhibitors were effective in inhibiting growth in ER+ ILC cell lines and synergized with endocrine therapy and similarly IGF1R/InsR inhibition reduced proliferation in ILC tumor explant culture.Conclusions: We provide evidence that loss of E-cadherin hyperactivates the IGF1R pathway and increases sensitivity to IGF1R/InsR targeted therapy, thus identifying the IGF1R pathway as a potential novel target in E-cadherin-deficient breast cancers. Clin Cancer Res; 24(20); 5165-77. ©2018 AACR.

Post-transcriptional regulation of cancer/testis antigen MAGEC2 expression by TRIM28 in tumor cells

BackgroundCancer/testis antigen MAGEC2 (also known as HCA587) is highly expressed in a wide variety of tumors and plays an active role in promoting growth and metastasis of tumor cells. However, little is known for the regulation of MAGEC2 expression in cancer cells.MethodsWestern blotting and quantitative RT-PCR were performed to analyze MAGEC2 expression. Co-immunoprecipitation assay was applied for detecting the endogenous interaction of MAGEC2 and TRIM28 in tumor cells. Overexpression and knockdown assays were used to examine the effects of TRIM28 on the expression of MAGEC2 protein. Immunohistochemistry (IHC) staining was performed in hepatocellular carcinoma patients to evaluate the association between the expression of MAGEC2 and TRIM28. Proteasome inhibitors MG132 or PS-341 and lysosome inhibitor Chloroquine (CQ) were used to inhibit proteasomal or lysosomal-mediated protein degradation respectively.ResultsWe demonstrate that MAGEC2 interacts with TRIM28 in melanoma cells and MAGEC2 expression in tumor cells depends on the expression of TRIM28. The expression level of MAGEC2 protein was significantly reduced when TRIM28 was depleted in tumor cells, and no changes were observed in MAGEC2 mRNA level. Furthermore, expression levels of MAGEC2 and TRIM28 are positively correlated in MAGEC2-positive human hepatocellular carcinoma tissues (p = 0.0011). Mechanistic studies indicate that the regulatory role of TRIM28 on MAGEC2 protein expression in tumor cells depends on proteasome-mediated pathway.ConclusionsOur findings show that TRIM28 is necessary for MAGEC2 expression in cancer cells, and TRIM28 may serve as a new potential target for immunotherapy of cancer.

Aider un parent âgé dépendant. Configurations d’aide et interactions dans les fratries en France

À partir de l’enquête Handicap-Santé, volet Ménages (Insee-Drees, 2008), nous étudions les configurations d’aide familiale autour d’un parent âgé et dépendant en France. Une première étape descriptive montre que l’aide apportée par les enfants est affectée par le statut conjugal du parent, la taille de la fratrie et le rang dans la fratrie. L’analyse se concentre ensuite sur les familles de 2 enfants et montre que les écarts de mobilisation observés selon le rang découlent de trois sources : les différences de caractéristiques individuelles entre aînés et cadets, l’impact différent de ces caractéristiques sur la décision d’aide, et enfin une différence dans l’ajustement des uns au comportement des autres (interactions endogènes). L’impact des caractéristiques familiales apparaît en effet relativement similaire pour les aînés et les cadets – en particulier la forte assignation au rôle d’aidant des femmes avec un frère –, mais le comportement des cadets fait apparaître en outre un arbitrage entre coûts et utilité de l’aide. Avec une définition de l’aide ciblée sur les tâches de la vie quotidienne, une seule explication majeure des différences demeure : l’asymétrie dans l’ajustement au comportement de l’autre enfant, à caractéristiques individuelles et familiales données.

Interceding role of institutional extension services on the livelihood impacts of drought tolerant maize technology adoption in Zimbabwe

The study investigates whether access to agricultural extension services enhances the well-known positive impact of adopting Drought Tolerant Maize (DTM) technology on livelihood outcomes; maize yield, output per capita, consumption and sales using a representative dataset of smallholder farming households from Zimbabwe. The empirical analysis adopts an instrumental variable regression model that incorporates an endogenous interaction term to capture the intermediary role of institutional extension services. Results reveal that access to agricultural extension services enhances the relationship between DTM adoption and maize yield, output per capita, and consumption but appears to weaken the association between DTM adoption and the amount of maize set aside for sale. In exploring the potential reasons why access to institutional extension services might enhance the DTM adoption-livelihood outcomes relationship, the results suggest mechanisms related to the use of basal fertilizers, use of organic manure, access to agricultural credit, use of certified DTM seed, access to general production and marketing information, weeding frequency and disease control which are more likely to be influenced by access to agricultural extension services. The findings suggest that policies targeted at improving DTM adoption as a climate-smart agricultural technology to improve resilience of smallholder maize farming households to climate variability and change must be complemented by revitalized agriculture extension services. Revitalization of extension services may come through capacity building of extension institutions, and their personnel, improving agricultural extension infrastructure, mobility of extension personnel, and increased financing to such institutions.

2 in 1: One-step Affinity Purification for the Parallel Analysis of Protein-Protein and Protein-Metabolite Complexes.

Cellular processes are regulated by interactions between biological molecules such as proteins, metabolites, and nucleic acids. While the investigation of protein-protein interactions (PPI) is no novelty, experimental approaches aiming to characterize endogenous protein-metabolite interactions (PMI) constitute a rather recent development. Herein, we present a protocol that allows simultaneous characterization of the PPI and PMI of a protein of choice, referred to as bait. Our protocol was optimized for Arabidopsis cell cultures and combines affinity purification (AP) with mass spectrometry (MS)-based protein and metabolite detection. In short, transgenic Arabidopsis lines, expressing bait protein fused to an affinity tag, are first lysed to obtain a native cellular extract. Anti-tag antibodies are used to pull down protein and metabolite partners of the bait protein. The affinity-purified complexes are extracted using a one-step methyl tert-butyl ether (MTBE)/methanol/water method. Whilst metabolites separate into either the polar or the hydrophobic phase, proteins can be found in the pellet. Both metabolites and proteins are then analyzed by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS or UPLC-MS/MS). Empty-vector (EV) control lines are used to exclude false positives. The major advantage of our protocol is that it enables identification of protein and metabolite partners of a target protein in parallel in near-physiological conditions (cellular lysate). The presented method is straightforward, fast, and can be easily adapted to biological systems other than plant cell cultures.

2 in 1: One-step Affinity Purification for the Parallel Analysis of Protein-Protein and Protein-Metabolite Complexes

Cellular processes are regulated by interactions between biological molecules such as proteins, metabolites, and nucleic acids. While the investigation of protein-protein interactions (PPI) is no novelty, experimental approaches aiming to characterize endogenous protein-metabolite interactions (PMI) constitute a rather recent development. Herein, we present a protocol that allows simultaneous characterization of the PPI and PMI of a protein of choice, referred to as bait. Our protocol was optimized for Arabidopsis cell cultures and combines affinity purification (AP) with mass spectrometry (MS)-based protein and metabolite detection. In short, transgenic Arabidopsis lines, expressing bait protein fused to an affinity tag, are first lysed to obtain a native cellular extract. Anti-tag antibodies are used to pull down protein and metabolite partners of the bait protein. The affinity-purified complexes are extracted using a one-step methyl tert-butyl ether (MTBE)/methanol/water method. Whilst metabolites separate into either the polar or the hydrophobic phase, proteins can be found in the pellet. Both metabolites and proteins are then analyzed by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS or UPLC-MS/MS). Empty-vector (EV) control lines are used to exclude false positives. The major advantage of our protocol is that it enables identification of protein and metabolite partners of a target protein in parallel in near-physiological conditions (cellular lysate). The presented method is straightforward, fast, and can be easily adapted to biological systems other than plant cell cultures.

Co-immunoprecipitation Assay Using Endogenous Nuclear Proteins from Cells Cultured Under Hypoxic Conditions.

Low oxygen levels (hypoxia) trigger a variety of adaptive responses with the Hypoxia-inducible factor 1 (HIF-1) complex acting as a master regulator. HIF-1 consists of a heterodimeric oxygen-regulated α subunit (HIF-1α) and constitutively expressed β subunit (HIF-1β) also known as aryl hydrocarbon receptor nuclear translocator (ARNT), regulating genes involved in diverse processes including angiogenesis, erythropoiesis and glycolysis. The identification of HIF-1 interacting proteins is key to the understanding of the hypoxia signaling pathway. Besides the regulation of HIF-1α stability, hypoxia also triggers the nuclear translocation of many transcription factors including HIF-1α and ARNT. Notably, most of the current methods used to study such protein-protein interactions (PPIs) are based on systems where protein levels are artificially increased through protein overexpression. Protein overexpression often leads to non-physiological results arising from temporal and spatial artifacts. Here we describe a modified co-immunoprecipitation protocol following hypoxia treatment using endogenous nuclear proteins, and as a proof of concept, to show the interaction between HIF-1α and ARNT. In this protocol, the hypoxic cells were harvested under hypoxic conditions and the Dulbecco's Phosphate-Buffered Saline (DPBS) wash buffer was also pre-equilibrated to hypoxic conditions before usage to mitigate protein degradation or protein complex dissociation during reoxygenation. In addition, the nuclear fractions were subsequently extracted to concentrate and stabilize endogenous nuclear proteins and avoid possible spurious results often seen during protein overexpression. This protocol can be used to demonstrate endogenous and native interactions between transcription factors and transcriptional co-regulators under hypoxic conditions.

Data Science Issues in Studying Protein–RNA Interactions with CLIP Technologies

An interplay of experimental and computational methods is required to achieve a comprehensive understanding of protein-RNA interactions. UV crosslinking and immunoprecipitation (CLIP) identifies endogenous interactions by sequencing RNA fragments that copurify with a selected RNA-binding protein under stringent conditions. Here we focus on approaches for the analysis of the resulting data and appraise the methods for peak calling, visualization, analysis, and computational modeling of protein-RNA binding sites. We advocate that the sensitivity and specificity of data be assessed in combination for computational quality control. Moreover, we demonstrate the value of analyzing sequence motif enrichment in peaks assigned from CLIP data and of visualizing RNA maps, which examine the positional distribution of peaks around regulated landmarks in transcripts. We use these to assess how variations in CLIP data quality and in different peak calling methods affect the insights into regulatory mechanisms. We conclude by discussing future opportunities for the computational analysis of protein-RNA interaction experiments.

A catenin-dependent balance between N-cadherin and E-cadherin controls neuroectodermal cell fate choices

Characterizing endogenous protein expression, interaction and function, this study identifies in vivo interactions and competitive balance between N-cadherin and E-cadherin in developing avian (Gallus gallus) neural and neural crest cells. Numerous cadherin proteins, including neural cadherin (Ncad) and epithelial cadherin (Ecad), are expressed in the developing neural plate as well as in neural crest cells as they delaminate from the newly closed neural tube. To clarify independent or coordinate function during development, we examined their expression in the cranial region. The results revealed surprising overlap and distinct localization of Ecad and Ncad in the neural tube. Using a proximity ligation assay and co-immunoprecipitation, we found that Ncad and Ecad formed heterotypic complexes in the developing neural tube, and that modulation of Ncad levels led to reciprocal gain or reduction of Ecad protein, which then alters ectodermal cell fate. Here, we demonstrate that the balance of Ecad and Ncad is dependent upon the availability of β-catenin proteins, and that alteration of either classical cadherin modifies the proportions of the neural crest and neuroectodermal cells that are specified.

Endogenous Cell Type–Specific Disrupted in Schizophrenia 1 Interactomes Reveal Protein Networks Associated With Neurodevelopmental Disorders

BackgroundDisrupted in schizophrenia 1 (DISC1) has been implicated in a number of psychiatric diseases along with neurodevelopmental phenotypes such as the proliferation and differentiation of neural progenitor cells. While there has been significant effort directed toward understanding the function of DISC1 through the determination of its protein-protein interactions within an in vitro setting, endogenous interactions involving DISC1 within a cell type–specific setting relevant to neural development remain unclear. MethodsUsing CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9) genome engineering technology, we inserted an endogenous 3X-FLAG tag at the C-terminus of the canonical DISC1 gene in human induced pluripotent stem cells (iPSCs). We further differentiated these cells and used affinity purification to determine protein-protein interactions involving DISC1 in iPSC-derived neural progenitor cells and astrocytes. ResultsWe were able to determine 151 novel cell type–specific proteins present in DISC1 endogenous interactomes. The DISC1 interactomes can be clustered into several subcomplexes that suggest novel DISC1 cell-specific functions. In addition, the DISC1 interactome in iPSC-derived neural progenitor cells associates in a connected network containing proteins found to harbor de novo mutations in patients affected by schizophrenia and contains a subset of novel interactions that are known to harbor syndromic mutations in neurodevelopmental disorders. ConclusionsEndogenous DISC1 interactomes within iPSC-derived human neural progenitor cells and astrocytes are able to provide context to DISC1 function in a cell type–specific setting relevant to neural development and enables the integration of psychiatric disease risk factors within a set of defined molecular functions.

The EEects of Official and Unoocial Information on Tax Compliance

The administration of tax policy has shifted its focus from enforcement to complementary instruments aimed at creating a social norm of tax compliance. In this paper we provide an analysis of the effects of the dissemination of information regarding the past degree of tax evasion at the social level on the current individual tax compliance behavior. We build an experiment where, for given levels of audit probabilities, fines and tax rates, subjects have to declare their income after receiving either a communication of the official average tax evasion rate or a private message from a group of randomly matched peers about their tax behavior. We use the experimental data to estimate a dynamic econometric model of tax evasion. The econometric model extends the Allingham–Sandmo–Yitzhaki tax evasion model to include self-consistency and endogenous social interactions among taxpayers. We find four main results. First, tax compliance is very persistent. Second, the higher the official past tax evasion rate the higher the degree of persistence: evaders are more likely to evade again, and compliant individuals are more likely to comply again. Third, when all peers communicate to have evaded (complied) in the past, both evaders and compliant individuals are more likely to evade (comply). Fourth, while both treatments, and especially the unofficial information treatment, are associated, in the context of our experiment, with a significantly larger growth in evasion intensity, the aggregate effect depends on the characteristics of the population. In countries with inherently low levels of tax evasion, official information can have beneficial effects by consolidating the behavior of compliant individuals. However, in countries with inherently high levels of tax evasion, official information can have detrimental effects by intensifying the behavior of evaders. In both cases, the impact of official information is magnified in the presence of strong peer effects.

Observation and contagion effects in cooperation: An experimental investigation

We experimentally disentangle two potential sources for endogenous social interactions effects. By comparing groups where the aggregate behavior is publicly observable with those where it is not we can measure the size of any endogenous observation effect. By comparing connected with disconnected groups we can measure the size of any endogenous contagion effect. Results are provided for both a coordination game and social dilemma. We find strong evidence of an endogenous observation effect in the coordination game but not social dilemma. We find no evidence of an endogenous contagion effect in either game. While our results point towards a conformity effect we argue that information on group behavior primarily acts as a coordinating device which may be reflected in changes in beliefs.